To achieve a high axial resolution of 2.6 ÃÂµm (n = 1 .38) in the optical coherence tomography system, a bandpass filter was used to limit the bandwidth of the light source to 81 nm. This also enabled the system to utilize the maximum A-line speed. Furthermore, the light source was cooled with liquid nitrogen to a very low temperature of -80 ÃÂC. This cooling process helped to reduce the power dissipation of the light source to 1 mW, which is a crucial factor for the optimal performance of an integrated circuit that exhibits quantum size effects. Therefore, two different experimental setups were designed and implemented to demonstrate the potential applications of quantum size effects in optical coherence tomography. According to 3eb670225b
Quantum size effects are phenomena that arise when the size of a material is comparable to the wavelength of electrons or photons. In such cases, the quantum mechanical behavior of the particles becomes dominant and leads to novel properties and applications. For example, quantum size effects can enhance the nonlinear optical response of materials, which can be exploited for frequency conversion, optical switching, and quantum information processing.
One of the applications of quantum size effects is quantum optical coherence tomography (Q-OCT), which is an imaging technique that uses nonclassical (quantum) light sources to generate high-resolution images based on the Hong-Ou-Mandel effect (HOM) . Q-OCT is similar to conventional OCT but uses a fourth-order interferometer that incorporates two photodetectors rather than a second-order interferometer that uses a single photodetector. The advantage of Q-OCT is that it can achieve a twofold improvement in axial resolution compared to classical OCT without sacrificing the signal-to-noise ratio.
In this work, we present two experimental setups that demonstrate the possibilities of quantum size effects in OCT. The first setup uses spectrally engineered photon pairs generated by spontaneous parametric down-conversion (SPDC) in a nonlinear crystal. The photon pairs are entangled in frequency and exhibit HOM interference when they are overlapped at a beam splitter. By scanning the relative delay between the photon pairs, we can obtain Q-OCT images of various samples, such as glass layers with manufactured transverse patterns and metal-coated biological specimens. The second setup uses a quantum light source based on an integrated circuit with quantum size properties. The light source consists of a superluminescent diode (SLD) that emits broadband light with a central wavelength of 800 nm and a bandwidth of 81 nm. The light source bandwidth was limited to 81 nm using a bandpass filter providing an axial resolution of 2.6 ÃÂµm (n = 1 .38). This allowed the use of the A-line speed. In addition, the light source was additionally cooled with liquid nitrogen to a temperature of -80 ÃÂC. Apparently, the cooling of the light source also made it possible to reduce the effective power dissipation to 1 mW, which is important for the efficient operation of an integrated circuit with quantum size properties. Thus, two experimental setups were created to demonstrate the possibilities of quantum size effects. According to 3eb670225b 0efd9a6b88